1. Technical Field
The present invention relates generally to computer devices and in particular to mechanisms for debugging computer devices. Still more particularly, the present invention relates to a method and device for providing enhanced debugging of JTAG-supported devices.
2. Description of the Related Art
Joint Test Action Group (JTAG) is the name commonly utilized for the IEEE 1149.1 standard (1990), with full name being “Standard Test Access Port and Boundary-Scan Architecture.” In one implementation, JTAG is provided within test access ports that are tulized for testing printed circuit boards via boundary scan. JTAG is currently being primarily used for testing sub-blocks of integrated circuits. JTAG is also used as a mechanism for debugging embedded systems, and provides a convenient “back door” into these system. When utilized as a debugging tool, an in-circuit emulator, which uses JTAG as the transport mechanism, enables a programmer to access an on-chip debug module, which is integrated into the CPU via JTAG. The debug module enables the programmer to debug the software of the embedded system.
One conventional method by which hardware-level debuggin operations are completed is by use of a device referred to as a POD. A POD is a hardware device, such as a system controller, that is self-initialized and may comprise a version of embedded Linux as its operating system. Use of conventional PODs adds an additional device to the overall test bench setup in a pre-JTAG environment, and the PODs are no longer being manufactured. Also, conventional PODs do not support JTAG debugging of a device under test. Since the PODs are no longer being manufactured, conventional debug methods continue to scan through the IEEE JTAG 1149.1 utilizing a system controller as a POD.
Consequently, the present invention recognizes that a software-level solution is required in order to continue being able to scan through the IEEE JTAG 1149.1 device for debugging purposes using a POD as the system controller. Software-enabled enhancements in the application of these JTAG PODs to enable advanced and/or more efficient debugging functions would be a welcomed development to existing methods that utilized conventional JTAG PODs to complete the connectivity to the device, which is to undergo the debug operation. With the movement away from continuing to manufacture PODS, the present invention recognizes and addresses the inherent problems in enabling debugging of JTAG devices that require these PODS for connectivity to a host system running the debug program.